While attending New York University, Harrison was introduced to many writers and theater artists such as Lou Gossett, Jr., Billy Dee Williams, Amiri Baraka (LeRoi Jones), and Ted Joans.
His students included Phylicia Rashad, Debbie Allen, Linda Goss, Pearl Cleage and Clinton Turner Davis.
While teaching at California State University, Sacramento (1970–1972), Harrison helped conceive and directed Melvin Van Peebles' "Ain't Supposed To Die a Natural Death" prior to its Broadway production,[1] and wrote his play The Great MacDaddy which was produced by the Negro Ensemble Company in 1973, and won an Obie Award.
Harrison taught at the University of Massachusetts Amherst from 1972 to 1976 before moving on to Columbia College Chicago in 1976 to work as Chair, Professor, and Writer in Residence at the Theatre Department until his retirement in 2002.
His first book of edited essays "The Modern Drama Footnote", was published in Amsterdam, as well as his plays, "Pavane for a Deadpan Minstrel" and "Tophat".
Other plays written, performed and directed in the Netherlands included, "The Post Clerks" and "The Experimental Leader", the latter becoming the center piece for his book commonly known as "Dialogue from the Opposition".
He has also written the text for the operetta, "Goree Crossing" with music by Olu Dara that was also given a concert performance at the Museum of Science and Industry in Chicago.
As Dramaturg for the ETA Theatre in Chicago, Harrison developed Marcia Leslie's highly successful play, "The Trial of One Short-sighted Black Woman vs Mammie Louise and Safreeta Mae".